I'm using the NC plate and still get a hanging idle 50% of the time at around 1400, takes more than a few seconds to drop to normal when it does. Is there a real fix for this? My last Mach got the plate and it just worked great, idle dropped fast & hard. tThis one still seems to float even when it drops.

I'm using the NC plate and still get a hanging idle 50% of the time at around 1400, takes more than a few seconds to drop to normal when it does. Is there a real fix for this? My last Mach got the plate and it just worked great, idle dropped fast & hard. tThis one still seems to float even when it drops.

Thanks.

Keep trying a smaller hole would be my advice. You might even have to go to just one hole instead of two like I did.

My mach has this same problem. Ill be driving and then Ill come to a stop and the RPMs will be at 1500, almost 2000 in some cases, and then after sitting there for maybe 4-5 seconds it drops down to like 600 and almost wants to die. Will the NC plate help?

Thanks so much for this fix! Took literally 45 minutes with this piece of scrap tin i had laying around. Drilled a 7/8 big hole and 5/16 "restricted" hole. Instantly noticed a difference upon test drive. Rpms drop like my last notchback did. Kudos!!

I did the fix for the hanging RPM problem on my '03 and it worked great. Not too long after, I put the Diablosport Predator on it and had no issues. A few months ago, I got some bad gas (we think) and pulled the tune off to help with the detonation. The RPMs hang bad now and it seems a million times worse than when I first got the car. Probably my mind playing tricks since the restrictor plate worked so well. Anyway, how do I fix this? The plate is still on there and the RPMs hang just a tad too much to ignore. I mean, it has completed messed with how I naturally drive the car. I'm assuming there's some flashing of the computer, uninstalling, and reinstalling of the plate in order but I just don't know. Can someone help me out?
Thanks.

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I did the fix for the hanging RPM problem on my '03 and it worked great. Not too long after, I put the Diablosport Predator on it and had no issues. A few months ago, I got some bad gas (we think) and pulled the tune off to help with the detonation. The RPMs hang bad now and it seems a million times worse than when I first got the car. Probably my mind playing tricks since the restrictor plate worked so well. Anyway, how do I fix this? The plate is still on there and the RPMs hang just a tad too much to ignore. I mean, it has completed messed with how I naturally drive the car. I'm assuming there's some flashing of the computer, uninstalling, and reinstalling of the plate in order but I just don't know. Can someone help me out?
Thanks.

My mach has this same problem. Ill be driving and then Ill come to a stop and the RPMs will be at 1500, almost 2000 in some cases, and then after sitting there for maybe 4-5 seconds it drops down to like 600 and almost wants to die. Will the NC plate help?

Mine did the same exact thing until I decided to replaced the IAC with a new one from Ford for about $100 or so. I cleaned the original IAC with brake part cleaner, but still didn't work. I guess it was real sticky?

Glad i stumbled on this thread. I've had my auto mach about 3 weeks or so, only driven it a few times. Every first startup this thing fires up aggressive and just stays there like 10-15 seconds it seems(prob a little exaggerated,lol), then finally comes down to idle. I'm always like wtf, thats a bit much and annoys the **** outta me,lol. Def. making one of these tomorrow!

Liked the way the rpms dropped to idle with the 9/32 hole, just not how it idled with max a/c on. So i opened it up to 11/32, its better with a/c.....but not how i liked it dropping with the 9/32 hole. Amazing how much it changes with a 1/32 of an inch!

*Edit..... after further review, the call on the field has been overturned! 11/32 hole is working great like had hoped.

I see this is an ancient thread, but I got mine from SR Customs off ebay, not sure of the hole size (though both holes were the same size). I like it!! It isn't an in your face difference, when I first crank car, rpms drop much quicker, idles steady and smOoth at 800 rpms (notice rpm steady, but shaker is moving more like a cam installed, again subtle). Turned on A/C and headlights, idle dropped to 700 and stayed between 700 and 750 rpms, everything is real smooth and steady. When I bump the throttle to 2-3k and let off, revs drop quicker, but again it isn't massive (reading all the post I think where I got mine the hole size must be conservative), but overall, I like it and for $6.30, a bargain and worth a risk, I brought the original gasket and an 8 mm wrench with me in case I had to swap back, but zero issues, though I only got about 125 miles on 1/2 tank , could be the 4:10 gears and my right foot , don't really see how this could affect gas mileage (????), but in general pretty easy mod that works as advertised, don't find that very often nowadays. My two cents, have a nice evening everyone!!

Disconnect battery cables (without creating a spark) for several hours, may take 2 or 3 tries. This apparently is the only way to reset the computer.
Also, pump the brake pedal before detaching battery cable. Will eliminate
any residual electricity.

Was reving up to 2500 consistently until I applied the above technique.
Idles like a charm now.

Go figure.

That is basically forcing the idle relearn. I can't imagine it takes hours. I've gotten the idle to relearn with just unplugging the negative cable for 15 minutes. I turn the lights on and hit the brakes, then reconnect the battery.

- Let the car idle and get up to normal operating temp. I wait until my fan comes on in the summer months.

- Then wait at least 1 minute after reaching normal operating temp.

- Turn on the AC to Max and let idle at least another minute.

- The turn off the AC and go for at least a 10 mile drive. I usually cruise around for 10 - 15 miles, then do one or two WOT's. The computer will still continue learning idle, but you should notice a big improvement from when you first started it up.

I do this any time I change my tune, or when the mechanic I go to disconnects the battery for any reason.

So I did this mod today, didn't use a metal plate but picked up one made out of mr gasket header gasket material, it came with 9/32 and 11/32 holes and immediately when we started the car up I could tell a difference, rpms come down much faster and the car kind of sounds like it has a mile cam now @ idol. Was not able to test drive the car but maybe tomorrow early before the N.Y.E. crazies hit the roads.